In recent years, house-service robots, such as a nursing robot and a house-keeping assist robot, have been vigorously developed. Since the house-service robot carries out jobs around a person unlike industrial robots, it is inevitable for the robot to come into contact with a person, and the robot needs to have a flexible structure from the viewpoint of safety and also needs to be flexible in its movements.
As one example of the robot device, a technique for ensuring control device operation precision has been proposed in which a contact force with a person, applied to a robot arm, is detected and, upon application of a great force to the arm, a restoring force is made smaller to ensure safety, while upon application of a small force to the arm, the restoring force is made greater to maintain the operation precision (see Patent Document 1).
Moreover, in a control device of an arm or leg control device that controls operations of the device by carrying out a force control or a positional control based on sensing information on a force sensor or a position/angle sensor attached to the device in an attempt to move an arm or a leg with the help of the device attached to the arm or leg, a technique has been proposed in which the load imposed to the arm or leg attached to the device is always monitored during operations of the driving device, and when the load onto the arm or leg has reached a value Fstart that is set to a value smaller than a preset excessive load value Flimit to the arm or leg, among all the degrees of freedom possessed by the operations of the driving device, an impedance constant in a direction of a certain degree of freedom is changed as the load value onto the arm or leg comes closer to the excessive load value Flimit so that the operation in the corresponding direction of the degree of freedom is made hypothetically free (see Patent Document 2).
Moreover, a technique has also been proposed in which, based on an inputted parameter of the arm or leg, a typical movement pattern is generated, and a target track of the limb driving device is calculated, and by using only the information on the parameter of the arm or leg, the limb driving device is switched to carry out either one of operations of a driven movement, a self-driving movement and a resistance movement (see Patent Document 3).
Patent Document 1: Japanese Unexamined Patent Publication No. 10-329071
Patent Document 2: Japanese Unexamined Patent Publication No. 9-154900
Patent Document 3: Japanese Unexamined Patent Publication No. 10-192350